Pieces of conduits, such as pipes or tubes, are welded together circumferentially to configure a required conduit length for being utilized in various purposes, including but not limited to, in heat exchangers or as transportation pipe lines, generally, utilized in various industries for the transportation of the chemicals, mineral oil and natural gases, and the like. Welding the pieces of conduits with each other requires much care, time and skill so that it is extraordinarily expensive. In welding the pieces of conduits there are great chances of deposition of weld material in and around a welding zone. Deposition of the weld material along the inner surfaces of the conduits may reduce the life of the welded conduits due to corrosions that may arise due to particles in the travelling through the welded conduits. Many attempts have been made to obviate such problems, and are still being made.
Generally, the welding of such conduit pieces is two steps process. In the first step, a base weld, generally known as a root layer, is made between the pieces of conduits in a relatively small gap, generally known as a root gap, therebetween. Base weld or the root layer is made at part of wall thickness adjacent to the inner surfaces of the conduit pieces. While forming the root layer there are great chances of the weld material to travel across the inner surfaces and get deposited. However, various modern technology are nowadays available which may prevent the deposition of the excess weld material, such as providing backing rings etc., along the welding zone. Such backing rings are provided on the inner surfaces along the root gap as a support, and thereafter the base weld is conducted. Such backing ring prevents the root weld of the root layer to travel across the inner surfaces of the conduit pieces in turn preventing weld material deposition thereon. Since the backing ring is partially melted, it has to be removed afterwards by machining.
Further, the second welding step is performed. In this step the root gap, after forming of the root layer, is filled by performing filler weld. The ‘root gap’ after forming of the root layer technically hereinafter referred to as a ‘gap.’ This gap is filled by repeatedly depositing filler weld electrodes. While performing the filler weld there are very likely chances of the root layer obtained in the first step of getting pressed out due the heat transfer effect of the filler weld. Generally, while performing the filler weld, compression stress on the root weld may be created, and therefore, there are likely chances that the root layer may plastically deform, which may lead to pressing out of the weld materials, such as the root weld or filler weld materials. Such pressing out of the weld material may reduce the life of the welded conduits due to corrosions as mentioned. Therefore in order to reduce such chances, generally machining of the deposited weld material are done wherein the excess root material are removed by machining manually or by utilizing any automatic device. Such machining is time consuming and cumbersome process that requires a lot of hands in turn increasing the costing over all of the welded conduits.
Accordingly, there exists a need of time effective, economic and handy ways for preventing deposition of the root weld in and around the welding zone of the conduit's inner surfaces, which precludes the required machining to remove the deposited root weld.